1. Field of the Invention
This invention relates to improved circuit interrupters. More particularly, the invention relates to a puffer type gas circuit breaker in which a flow of gas is created between an arcing contact and a nozzle which blows against an arc generated between a movable arcing contact and a stationary arcing contact thereby to extinguish the arc. Yet more specifically, the invention relates to improved arcing contacts and gas passage forming members provided in the vicinity of the arcing contact.
2. Description of the Prior Art
In a puffer type gas circuit breaker, the pressure of the gas in the puffer cylinder is increased by the utilization of the principle of a bellows so that a flow of gas is created in the gas passageway between the movable arcing contact and the nozzle which blows against an electrical arc generated between the movable arcing contact and the stationary contact thereby to extinguish the arc.
A variety of puffer type gas circuit breakers are available. One example of a conventional puffer type gas circuit breakers is as shown in FIGS. 1 and 2. As is seen in FIGS. 1 and 2, the gas, for example, air or SF.sub.6 gas, passes through a gas passageway 75 between a nozzle 10 and a gas guide 23 and then is directed against an electric arc 25 which is generated between a finger-shaped movable arcing contact 7 and a stationary arcing contact 2. As is apparent from FIGS. 1 and 2, in the conventional puffer type gas circuit breaker, the gas which is not heated by the arc yet is not substantially applied to the movable arcing contact 7; that is, the gas heated by the arc is applied to the movable arcing contact 7 thereby increasing the temperature of the contact 7. Moreover, in this structure gas guide 23 is in the form of a cylinder made of an insulating material. Accordingly, it necessarily has a large wall thickness and therefore the gas guide 23 is liable to disturb the flow of gas which is applied to the arc.